What research has been done in the domain of "Identifying sarcasm in text"?
The following survey article by researchers from IIT Bombay summarizes recent advances in sarcasm detection: Arxiv link.

In reference to your question, I do not think it is considered either extraordinarily difficult or open-ended. While it does introduce ambiguity that computers cannot yet handle, Humans are easily able to understand sarcasm, and are thus able to label datasets for sarcasm detection.